Capsules are known that are intended for use in dispensing machines, that consist of disposable and single-dose containers comprising an outer casing, made of plastics impermeable to liquids and to gases and having the shape of a beaker or cup. The casing has a bottom wall and a side wall defining an upper opening through which the product can be inserted from which to obtain the beverage. The upper opening is closed hermetically by a covering element, typically a film of aluminum or of plastics, so as to seal the product inside the container. The covering element is generally fixed to a peripheral and annular flange-shaped bottom of the casing, which is opposite the bottom wall and arranged around the upper opening.
In the bottom wall a lower opening is obtained through which the beverage is dispensed. The lower opening is closed hermetically by a closing element, typically a film of aluminum or of plastics like the covering element of the upper opening.
The capsule is perforable to enable the pressurized liquid, typically water, to be delivered inside the capsule. In particular, the covering element is perforable by suitable means of a dispensing machine to enable pressurized liquid to be delivered into the capsule.
The beverage is dispensed by breaking the closing element, which occurs when the pressure inside the capsule exceeds a preset value, depending on the mechanical resistance of the closing element.
One problem that occurs with this type of capsule arises from the fact that the breakage of the closing element causes a sudden change of pressure inside the capsule, which can trigger the so-called “water hammer”, which can lead to the capsule exploding and also to damage to the hydraulic circuit of the dispensing machine, because the pressure waves generated by the water hammer can propagate in the nozzles that deliver the pressurized liquid to the capsule and, from the nozzles, to the entire hydraulic circuit of the dispensing machine.
A further problem that occurs with this type of capsule is due to the fact that, when the closing element breaks, the pressurized liquid exits from the capsule at high speed, and reaching a container intended to receive the beverage can cause squirts that exit the container, soiling the dispensing machine and the zone surrounding the container.
In order to overcome the aforesaid problems, capsules have been designed that are provided, downstream of the lower opening, with one or more labyrinth paths, the object of which is to decrease the speed of the beverage leaving the capsule, to avoid the formation of squirts when the beverage reaches the container intended to receive the beverage, and generate load losses that make the pressure drop less sudden, i.e. more progressive, inside the capsule at the moment of breakage of the closing element of the lower opening.
Manufacturing these labyrinth paths is nevertheless expensive and greatly increases the cost of manufacturing of the capsule, in addition to not fully guaranteeing that a water hammer does not occur when the closing element breaks.
From patent application 102014902241964, in the name of the same applicant, a capsule is further known in which, below the lower opening, a chamber is obtained in which a damping element is arranged for controlling the exit speed of the beverage.
The damping element is able to reduce, but not to eliminate completely, the risk of a water hammer occurring, when the closing element is broken.